I'm so excited I didn't think there was going to be an opportunity for like you get to handle liquid oxygen so this was shown for the liquid oxygen okay and then with this way I feel nervous do you know why I'm here at MIT with one of the technicians from the physics demo group preparing to pour liquid oxygen over a magnetic field created by some super strong electricity let me repeat that liquid oxygen I never seem liquid oxygen and they let me pour it by the way I'm Diana and you're watching physics girl okay oh my gosh I can't I can't believe this demo it is really cool I was freaking out because the liquid was just hanging there between two magnetized pieces of metal liquids are supposed to do that in my experience but this liquid was just hanging there in a magnetic field created by electricity and as soon as you turn off the electricity let's see what happens there's no surface tension effect here to have some new dangers I heard it awesome oh my gosh can I do it again in all my time at MIT no professor ever did this demo for us so disappointing because the physics here is really cool first thing there are electromagnets which are made by running electricity through coils of wire to coils that when we pass a DC current through them it's going to create a magnetic field between these two giant pieces of metal these are what are becoming magnetized okay by the DC current running through these coils the result is a strong magnetic field around the metal pieces but most importantly in the gap between them it's just like a strong magnetic field between two permanent magnets except you can turn it off now if you poured liquid nitrogen or water or alcohol in between the two pieces of metal you wouldn't get any of it hanging around and party you might get a few droplets of water sticking to the surface because of surface tension but though the liquid oxygen has surface tension it's not what's causing the liquid to stick to the metal here because the oxygen boils away too quickly at the interface it's the Leidenfrost effect then why is the oxygen hanging out well it's because different materials have different responses to external magnetic field your face is pretty unresponsive to a strong magnetic field iron is visibly responsive to an external magnetic field I don't recommend doing that with your neodymium magnets hot iron acts differently as we'll see when we heat up this piece of metal with a blowtorch yeah stay tuned for that but liquids don't usually visibly react to magnetic fields and yet liquid oxygen clearly does by the way liquid oxygen is oxygen cooled down below 90 Kelvin in Fahrenheit that's when your spit freezes way before it hits the ground the liquid oxygen has this property called para magnetism it reacts mildly to an external magnetic field and all the little mini magnets that make up the oxygen align with the external magnetic field these mini magnets I'm talking about are basically the little magnetic moments of the electrons in the oxygens atom you can really think of a magnet being made up of tiny tiny tiny tiny little magnets all aligned in the same direction but in a paramagnetic material as soon as you turn off the external magnetic field all those little mini magnets go back to pointing in random directions now iron in turn has ferromagnetic properties so all this little mini magnet align strongly with an external magnetic field and even keep some of that alignment after the field is removed but there's a point when even the mini magnets in ferromagnetic materials won't align and it's when you get them hot enough yep so this is just a little bit and then we have a thermally insulating place so that we don't damage our magnet oh that's okay that's not stuck on there that yeah like a lot we're heating the iron medal here past what's called the Curie point there's too much energy too much random motion of the magnetic moments for them to align and so the iron no longer sticks to the magnet this is just like how it's impossible to get a bunch of preschoolers to line up if they have a ton of energy but if you freeze them I mean metaphorically if you let the iron cool back down cool it will actually to the man the Curie point of iron is around a thousand forty-three Kelvin which is incidentally around the temperature when iron starts to get hot enough to admit visible light which is why it's glowing here I really enjoy these demonstrations and we tried some other demonstrations and some other stuff with these demos can you can you just like wow there's a big spark there too so that's back EMF we actually have one that will do a huge back in that we lift it oh you just real know how we did wheel that out I'm going to save that demo for next week so thank you to the Technical Services Group at MIT they were amazing they made all of this possible thank you guys for watching this video subscribe if you want more physics and hits a notification bell if you want to know when my videos come out